What is Swimmer's Itch?

Each summer, a skin rash, commonly called Swimmers Itch (also called cercarial dermatitis),
is reported by swimmers in many of the lakes found throughout Washington State,
particularly in the western and northern regions. It is caused by an allergic reaction
to a parasite (cercariae) that has burrowed into the swimmer’s skin.

Where do the parasites come from?

The adult parasite exists in the blood of infected
water fowl, such as ducks, geese, swans and gulls and
in aquatic animals such as beaver and muskrat. The
eggs produced by the adult parasite develop in the
intestinal tract of its host and are excreted in the
feces of the bird or animal into the water. These
eggs can hatch in the water, releasing small free-swimming
larvae which swim in search of its second host, a certain
species of aquatic snail. The larvae infect the snail,
multiply and develop into a different type of larvae. This
larval form then swims about searching for a suitable
host (bird or aquatic animal) to continue the life cycle. There is no way to know how long the water may be unsafe. Larvae generally
survive for 24 hours once they are released from the
snail. However, an infected snail will continue to
produce cercariae throughout the remainder of its life.

Who is at risk of Swimmer's Itch?

Anyone who swims or wades in infested waters
may be at risk. The larvae are more likely to be
present in shallow water by the shoreline,
therefore children are most often affected because they
tend to swim, play, and wade in shallow water more than
adults.

What are
the signs and symptoms of Swimmer's Itch?

While humans are not natural hosts, we
can become involved accidentally. A small
amount of water remains on the skin when a swimmer
leaves the water. As the water evaporates or runs off,
the larvae that are present quickly burrow into the
skin. Human skin and tissue is not a suitable
environment for these parasites, therefore the larvae
soon die. The presence of the foreign protein material
under the skin causes an allergic type of reaction,
resulting in the rash and itching. Symptoms may occur
within minutes to days after swimming in contaminated
water. Symptoms include:

Tingling, burning, or intense itching of the skin

Small reddish pimples appear within 12 hours which may become small
blisters or pustules

The itching is intense and causes considerable scratching.
Scratching the infected areas may result in secondary bacterial infection. After
a week or so, the itching subsides and the lesions heal,
however in some instances, recovery takes as long as 30
days. Because swimmer’s itch is caused by an allergic
reaction to infection, the more often you swim or wade
in contaminated water, the more likely you are to
develop more serious symptoms. The greater the number of
exposures to contaminated water, the more intense and
immediate symptoms of swimmer’s itch will be.

What is the treatment for Swimmer's Itch?

The following may relieve the itching:

Corticosteroid cream

Apply cool compresses to the affected areas

Bathe in Epson salts or baking soda

Soak in colloidal oatmeal baths or use lotions such as Aveeno

Apply baking soda paste to the rash (stir water into baking soda until it reaches a paste-like consistency)

Use an anti-itch lotion, such as calamine lotion

Consult your doctor for additional information on treatment.

Is there a way to prevent Swimmer's Itch

The following easy steps can be taken to prevent Swimmer’s Itch

Avoid swimming in areas where there is evidence of ducks and geese.

Do not swim or wade in marshy areas where snails are commonly found.

Shower, towel off, or wipe water off the body with the palms of the hands immediately following swimming.